| dc.description.abstract | This research investigates and addresses potential process safety issues with scaling up two-dimensional nanomaterial synthesis. The area of nanomaterial, particularly MXenes and graphite oxide (GO), was chosen because of the growing research interest in commercializing these materials. MXenes are metal carbides with promising applications in energy storage and gas sensors. Here we investigate hazards associated with MXene production, including MAX phase synthesis from raw materials, etching of MAX phase to MXene clay, exfoliation to MXene nanosheets, and post-processing of MXenes with Ti3C2Tx as a model species. The major hazards in MXene synthesis are the potential for dust ignition, runaway reactions, and toxic chemical exposure. This study is intended to facilitate safer MXene synthesis across various levels of scale-up, from large laboratory batches to commercial production.
GO is a precursor to making bulk quantities of graphene-like materials consistently and economically. Prior studies show that GO has the potential to undergo explosive decomposition. In this study, a reactive system screening tool was used to track the temperature and pressure of the explosive decomposition of GO. The data showed that the explosive decomposition temperature of GO strongly depends on sample size and surface area. Finally, the Frank-Kamenetskii model was used to predict the critical mass necessary for GO to undergo explosive decomposition, the model predicted the mass within a factor of experimental data. The results of this study are beneficial in assessing the hazards of bulk GO during storage and handling.
Finally, a reaction calorimeter is used to report the heat of oxidation reaction in the modified Hummers’ method to synthesize GO. The heat of reaction increased when graphite is soaked in sulfuric acid for an extended time, which gave more basal functionalization compared to an oxidation process without an extended soaking of graphite in acid. The study showed the heat of solution and reaction is high enough to reach the reported unstable temperature of Mn2O7, but the amount of Mn2O7 generated in a typical modified Hummers’ method is dilute enough to avoid a violent reaction at 55 °C.
In addition to investigating the safety considerations, in this dissertation, an electro-chemical exfoliation (ECE) method is studied to synthesize graphene-like product from alternative carbon sources such as petroleum-derived cokes. | en |
